Add debug comment to diffs indicating generator backend, node, and time.

May help tracking down the awful bugs we've been seeing more of lately.

diff --git a/includes/DifferenceEngine.php b/includes/DifferenceEngine.php
index 49f9e65..93b3771 100644 (file)
--- a/includes/DifferenceEngine.php
+++ b/includes/DifferenceEngine.php
@@ -480,7 +480,8 @@ CONTROL;
                        if( !function_exists( 'wikidiff_do_diff' ) ) {
                                dl('php_wikidiff.so');
                        }
-                       return $wgContLang->unsegementForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) );
+                       return $wgContLang->unsegementForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
+                               $this->debug( 'wikidiff1' );
                }
 
                if ( $wgExternalDiffEngine == 'wikidiff2' ) {
@@ -494,6 +495,7 @@ CONTROL;
                        if ( function_exists( 'wikidiff2_do_diff' ) ) {
                                wfProfileIn( 'wikidiff2_do_diff' );
                                $text = wikidiff2_do_diff( $otext, $ntext, 2 );
+                               $text .= $this->debug( 'wikidiff2' );
                                wfProfileOut( 'wikidiff2_do_diff' );
                                return $text;
                        }
@@ -521,6 +523,7 @@ CONTROL;
                        $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
                        wfProfileIn( __METHOD__ . "-shellexec" );
                        $difftext = wfShellExec( $cmd );
+                       $difftext .= $this->debug( "external $wgExternalDiffEngine" );
                        wfProfileOut( __METHOD__ . "-shellexec" );
                        unlink( $tempName1 );
                        unlink( $tempName2 );
@@ -532,9 +535,28 @@ CONTROL;
                $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
                $diffs = new Diff( $ota, $nta );
                $formatter = new TableDiffFormatter();
-               return $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
+               return $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) ) .
+                       $this->debug();
+       }
+       
+       /**
+        * Generate a debug comment indicating diff generating time,
+        * server node, and generator backend.
+        */
+       protected function debug( $generator="internal" ) {
+               global $wgShowHostnames, $wgNodeName;
+               $data = array( $generator );
+               if( $wgShowHostnames ) {
+                       $data[] = $wgNodeName;
+               }
+               $data[] = wfTimestamp( TS_DB );
+               return "<!-- diff generator: " .
+                       implode( " ",
+                               array_map(
+                                       "htmlspecialchars",
+                                               $data ) ) .
+                       " -->\n";
        }
-
 
        /**
         * Replace line numbers with the text in the user's language